Hard coating film for forming tool and forming tool

Abstract

A hard coating film excellent in wear resistance and seizure resistance for coating a forming tool of a Cr-containing iron-base alloy includes a first coating layer A of a thickness between 1 and 10 μm formed on the forming tool and a second coating layer B of a thickness between 2 and 10 μm overlying the coating layer A. The first coating layer A is a film of Cr_1-xM_x(B_aC_bN_1-a-b) meeting conditions expressed by expressions: 0≦x≦0.7, 0≦a≦0.2 and 0≦b≦0.5, where M is at least one element among W, V, Mo, Nb, Ti and Al, x is atomic ratio of M, a is atomic ratio of B and b is atomic ratio of C, and the second coating layer B is a film of Ti_1-X-Y-ZCr_XAl_YL_Z(B_BC_AN_1-A-B) meeting conditions expressed by expressions: 0≦1−X−Y−Z≦0.5, 0<X≦0.5, 0.4≦Y≦0.7, 0≦Z≦0.15, 0≦A≦0.5, and 0≦B≦0.2, where L is at least either of Si and Y, X is atomic ratio of Cr, Y is atomic ratio of Al, Z is atomic ratio of L, A is atomic ratio of C and B is atomic ratio of B.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a hard coating film for a forming tool and a forming tool coated with the same. More particularly, the present invention relates to a hard coating film, for a forming tool, excellent in wear resistance and a forming tool coated with the same.[0003]2. Description of the Related Art[0004]It has been usual to improve the wear resistance and the seizure resistance of a forming tool, such as a forming die, by a nitriding process. Recently, studies have been made to improve the wear resistance and the seizure resistance of a forming tool by a vapor-phase coating method, such as a PVD process. A tool disclosed in, for example, JP-A 2000-144376 (Cited reference 1) is coated with a composite nitride containing at least two elements among Cr, Al, Ti and V to improve sliding performance. Surface-coated forming dies excellent in wear resistance and seizure resistance disclosed in JP-A 2002-307128 (C...

AI Technical Summary

Benefits of technology

[0014]The hard coating film of the present invention for the forming tool is superior to the conventional surface coating layer in wear resistance and seizure resistance and is suitable for coating a forming tool, such as a forming die, to improve the durability of the forming tool. The forming tool of the present invention excellent in wear resistance and seizure resistance is suitable for use as a forming die or the like.

Problems solved by technology

Although the composite nitride containing at least two elements among Cr, Al, Ti and V disclosed in Cited reference 1 has a high hardness and is excellent in wear resistance, the composite nitride is unsatisfactory in seizure resistance.

A tool coated with a film of this composite nitride cannot withstand a severe working process, such as a metal forming process that exerts high pressure on the surface of the tool.

Although a nitride, a carbide and a carbonitride of at least one element among Ti, V, Al, Cr and Si disclosed in Cited reference 2 have high hardness, the same are unsatisfactory in seizure resistance.

However, since the sulfide is soft, the sulfide coating wears with time of use is unsatisfactory in durability.

Although this film, similarly to the sulfide film, is effective in improving sliding performance at an early stage of use, this film is unsatisfactory in durability.

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